Last summer i hit a rock and broke my XR. I got a used XR upper and got an IMCO 2" shorty. I had my mechanic go through both upper and lower and new bearings and such, said both gear sets were like new. I also put in a new vertical shaft. After I got my drive together I threw a rod on a new engine build (warranty job at least). So with the new drive last year I maybe ran 20 hours. Now i got my boat back with the new motor and the upper gear set broke while I was breaking in the new motor (less than 2 hours of run time). Took out the lower gear set to but my cases and shafts are all ok. So, i borrow a friends Standard Bravo 1 to get a little run time on the new engine. after about 4 hours of running I now have a vibration in the drive and a thumping noise when in forward. No clunks or loud bangs and goes in and out of gear fine and doesn’t make any noise when in reverse, only forward? 2 drives in 5 hours since engine was out, could motor mounts not be aligned correctly? I do not have alignment tool to check yet but was curious if there was any correlation with these drive issues and the engine in and out? Also, this is now 2 XR's that have failed and was curious if i run a stock Bravo upper with the IMCO shortie and my new vertical shaft? My engine is procharged to right around 700 hp and i think I’m gonna take the charger off and back it down to the high 500's with torque around the same and naturally asperated so I can run without breaking drives. THANKS for any advice fellas, this has been a very frustrating process...

Something is not correct. If you are easy on the throttle when getting on plane, staying under 3000rpm, you should not be breaking drives that fast. I had 2 old style bravo 1 drives with the 1 inch prop shaft on a 12,000lb 38 foot Cigarette Top Gun and I never blew a drive. 5 blade Maximus props. 605hp each side. 502 blocks with B&M blowers. I had Halo Max drive showers though. Maybe it's because you have one engine. You should use your tabs getting on plane.

I always take my time getting on plane and usually dont go over 3000 until on plane. My boat plains fairly quick so its easy to just roll into it. Just in a bad place because I cant afford to be replacing drives every 10 hours

If that's the case, I would bring your boat to a professional, certified location with a good reputation. The only thing bad about that is that you will most likely not get your boat back until summer is over. I have a funny feeling they are going to pull your motor. Once they do that, it's over. My boat has been in the shop since the 1st week in Jan. Getting Arneson Drives. I'm not the only one that I talk to that has had their boat in the shop for months and months. They are all pretty much the same.

If you want I am local to you and I have a real kick ass alignment tool you can borrow , I could also look at your drive and see what happened, who built it? pm me with your phone number, Smiitty

I suspect the first drive was stressed when the rod went in the new motor, that may be why it let go after a short run with the second motor.. The other drive, well have Smitty take a look at it. He can make right..

Dick

Thats a very good possibility. I have missed Smitty a few times he has called, I need to get a hold of him and see what he thinks. Thanks for the replys fellas